The present invention relates generally to liquid fuel dispensing systems utilizing suction pumps, and more particularly to pressure regulators for regulating line pressure on the inlet side of the pump.
Fuel dispensing stations generally include a liquid fuel reservoir, a plurality of remote individual island dispensers, and a large amount of piping to produce the fuel lines that extend from the reservoir to the remote dispensers. Each individual dispenser includes a conventional suction pump and a pressure regulator valve located on the inlet side of the suction pump to control line pressure. The regulator valve is normally closed so that head pressure of the fuel storage tank cannot cause fuel to flow through the suction pump, into the air eliminator chamber, out the air vent tube, and onto the ground. The valve only opens when a vacuum is drawn by the suction pump, e.g. when the pump is actuated by a customer, who desires to deliver fuel through the hose and nozzle to a vehicle or a portable fuel can.
The regulator valve may be used in booster systems with a submerged pump in an underground fuel storage tank. Alternatively, the valve may be used in power-gravity installations having an above-ground storage tank. One such pressure regulator valve that has performed effectively in both systems is the Model 52 Pressure Regulator, commercially available from Tokheim Corporation in Fort Wayne, Ind.
One problem associated primarily with above-ground storage tanks is that the fuel stored therein is generally susceptible to atmospheric conditions, and especially to solar heating resulting in thermal expansion of the fuel. Since the regulator valve is generally closed, fuel in the piping on the inlet side of the valve can develop pressures of 1,000 psi or more, which is sufficient to blow out the gaskets in the regulator valve thereby permitting fuel to drain onto the ground.
It is desired to provide a regulator valve, wherein such problem can be avoided.